Pressure-Induced Confined Metal from the Mott InsulatorSr3Ir2O7

Ding, Yang,Yang, Liuxiang,Chen, Cheng-Chien,Kim, Heung-Sik,Han, Myung Joon,Luo, Wei,Feng, Zhenxing,Upton, Mary,Casa, Diego,Kim, Jungho,Gog, Thomas,Zeng, Zhidan,Cao, Gang,Mao, Ho-kwang,van Veenendaal, American Physical Society 2016 Physical Review Letters Vol.116 No.21

<P>The spin-orbit Mott insulator Sr3Ir2O7 provides a fascinating playground to explore insulator-metal transition driven by intertwined charge, spin, and lattice degrees of freedom. Here, we report high-pressure electric resistance and resonant inelastic x-ray scattering measurements on single-crystal Sr3Ir2O7 up to 63-65 GPa at 300 K. The material becomes a confined metal at 59.5 GPa, showing metallicity in the ab plane but an insulating behavior along the c axis. Such an unusual phenomenon resembles the strange metal phase in cuprate superconductors. Since there is no sign of the collapse of spin-orbit or Coulomb interactions in x-ray measurements, this novel insulator-metal transition is potentially driven by a first-order structural change at nearby pressures. Our discovery points to a new approach for synthesizing functional materials.</P>

소형위성 발사 서비스 시장 지형

양정호(Jungho Yang),정호진(Hojin Jung),박정호(Jung Ho Park),정혜진(Hyejin Jeong) 한국추진공학회 2020 한국추진공학회 학술대회논문집 Vol.2020 No.11

본 논문은 향후 크게 성장할 것으로 예상되는 소형위성 시장과 소형위성을 임무 궤도까지 수송하기 위한 글로벌 발사 서비스 시장의 지형을 탐색하고 그 특성을 이해하는데 초점을 두었다. 이를 위해 먼저, 지난 10년(‘10~’19) 기록과 향후 10년(‘20~’29) 간의 소형위성 시장 발전 추세를 살펴보았고, 현재 상업 발사서비스에 운용 중인 글로벌 민간 소형 발사체의 발사 신뢰성, 비용 경쟁력 등을 조사하였다. 또한, 글로벌 소형위성 운영자가 어느 국가의 발사체를 이용해왔고 향후 이용할 것인지를 파악하기 위하여 발사 서비스 수요-공급 거래 지형을 네트워크 분석기법을 통해 확인하였다. 그 결과, 그 동안 많은 경우 경제성 및 발사 성공률 등과 같은 시장 기준만으로 거래 결정이 이루어지지 않은 것을 추측해 볼 수 있었다. 우리나라는 제3차 우주개발진흥기본계획에 따라 한국형발사체 개발과 소형 발사체 핵심기술 선행연구를 진행하고 있다. 향후 글로벌 시장 진출을 염두에 두고 관련 환경을 미리 파악하여 발사 시장만이 갖는 수요-공급 고유 특성과 시장 경쟁 시 불리하게 작용할 수 있는 요소들을 이해하는 것이 필요하겠다. This paper is focused on exploring the enlarging smallsat market for the period of 2010~2029 and contributing to the better understanding of the landscape of the global launch services. We fisrt looked into how fast the small satellites market has evolved in terms of their launched number since 2010 and the estimates until 2029. In addition, we investigated the success rates and cost competitiveness of a few globally competitive private small launchers currently being used in commercial launch services. In order to confirm the nations of the launchers global smallsat operators have used and will use, we analyzed how the demand-supply of launch service has been matched, which we refer to as the transaction landscape of the launch service. As a result, we have come to reach the presumption that a number of launch contracts might have been decisively made with other than market factors such as launch cost and the launch success rate. In line with the 3rd Basic Plan for Promotion of Space Development, Korea has been developing the KSLV-II and has just begun the preliminary research on core technologies necessary for the development of the small-lift launch vehicle. If joining the competition in the global launch market when launch vehicles are ready is being considered, we believe that comprehending the related environment properly and the factors that have to be addressed is essential.

약한 광중합과 열경화를 이용한 자유곡면에 미세 표면주름제작

양정호(Jungho Yang),조지준(Zhijun Zhao),박상후(Sanghu Park) 대한기계학회 2015 대한기계학회 춘추학술대회 Vol.2015 No.11

Highly Condensed Epoxy−Oligosiloxane-Based Hybrid Material for Transparent Low-<i>k</i> Dielectric Coatings

Yang, SeungCheol,Kwak, Seung-Yeon,Jin, JungHo,Bae, Byeong-Soo American Chemical Society 2009 ACS APPLIED MATERIALS & INTERFACES Vol.1 No.7

<P>A highly condensed epoxy-oligosiloxane resin was synthesized using a sol-gel condensation reaction of (3-glycidoxypropyl)trimethoxysilane and diphenylsilanediol in the presence of solvent. A higher degree of condensation and a larger molecular size of oligosiloxanes were achieved compared to a condensation reaction without the addition of a solvent. The epoxy-hybrimer coating film was fabricated by the spin coating and thermal curing of the synthesized oligosiloxane resin. The leakage current density and the dielectric constant decreased from 25.9 to 7.6 nA cm(-2) and from 3.16 to 3.03, respectively, by using the solvent in the preparation. The hybrimer coating film of a highly condensed oligosiloxane resin had a high transmittance of over 90% in a wavelength between 300 and 800 nm. Thus, the epoxy-hybrimer coating film can be utilized as the passivation layer in the thin-film transistor.</P>

Thermally resistant UV-curable epoxy–siloxane hybrid materials for light emitting diode (LED) encapsulation

Yang, SeungCheol,Kwak, Seung-Yeon,Jin, JungHo,Kim, Joon-Soo,Choi, Yongwon,Paik, Kyung-Wook,Bae, Byeong-Soo The Royal Society of Chemistry 2012 Journal of materials chemistry Vol.22 No.18

<P>A UV-curable epoxy–siloxane hybrid material (epoxy hybrimer) was fabricated by photo-cationic polymerization of a sol–gel derived cyclo-aliphatic epoxy oligosiloxane (CAEO) blended with oxetane cross-linker in the presence of an onium salt. Antioxidants for fabrication of the UV-curable epoxy hybrimer with high thermal resistance against yellowing were incorporated in the UV-curable epoxy hybrimer. The UV-curable epoxy hybrimer with the antioxidants showed high thermal resistance without yellowing during 120 °C thermal aging. High thermal resistance of the UV-curable epoxy hybrimer was similar and higher compared to those of commercial thermally curable silicone and UV-curable epoxy LED encapsulants, respectively. The thermally resistant UV-curable epoxy hybrimer was successfully encapsulated on a LED without any cracking or delamination, and maintained a flat surface on the LED without distortion of the designed flat shape. Before/after thermal and blue light aging, the performance of the LED encapsulated by the UV-curable epoxy hybrimer was not changed. On the basis of its excellent properties as a LED encapsulant, the UV-curable epoxy hybrimer can be utilized as a UV-curable LED encapsulant for white LEDs.</P> <P>Graphic Abstract</P><P>A UV-curable epoxy–siloxane hybrid material has comparable thermal resistance with a thermally curable silicone LED encapsulant. The UV-curable epoxy–siloxane hybrid material successfully encapsulated a blue LED without any delamination or cracking. The LED encapsulated by the hybrid material is ordinarily emitted without blue LED performance degradation. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2jm16355a'> </P>

Expression of a Bacillus subtilis Endoglucanase in Protease-Deficient Bacillus subtilis Strains

YANG, MI-JEONG,JUNG, SUN-HWA,SHIN, EUN-SUN,KIM, JUNGHO,YUN, HAN DAE,WONG, SUI-LAM,KIM, HOON 한국미생물 · 생명공학회 2004 Journal of microbiology and biotechnology Vol.14 No.2

Three extracellular protease-deficient Bacillus subtilis strains were transformed with the plasmid pCK98 containing the endo-β-l,4-glucanase (Eng) gene of B. suhtilis BSE616. The three transformants, B. subtilis DB 104 (pCK98), WB600 (pCK98) and WB700 (pCK98), produced the same high level of enzyme activity and showed similar patterns of cell growth and enzyme production. When B. subtilis DB104 (pCK98), a two-extracellular protease deficient strain, was cultured for 22 h, almost all the secreted enzyme was found to be in the completely cleaved form by both activity staining and Western blotting studies. B. subtilis WB600 (pCK98), a six- extracellular protease-deficient strain, produced a partially cleaved form in addition to the intact fonn of the enzyme, although the degree of internal cleavage of the enzyme was greatly reduced. With B. subtilis WB700 (pCK98), a seven-extracellular protease-deficient strain, almost all the enzyme was produced as the intact uncleaved form. This study illustrates that a role of the Vpr protease is to degrade foreign proteins produced in B. subtilis and WB700 is a suitable expression system for producing the intact form of the Eng and other foreign proteins that may lose at least part of their efficacy due to internal proteolytic cleavage.

DNA Damage-inducible Phosphorylation of p53 at Ser20 is Required for p53 Stabilization

Yang, Dong-Hwa,Rhee, Byung-Kirl,Yim, Tae-Hee,Lee, Hye-Jin,Kim, Jungho The Korean Society for Integrative Biology 2002 Korean journal of biological sciences Vol.6 No.3

The p53 tumor suppressor gene is among the most frequently mutated and studied genes in human cancer, but the mechanisms by which it sur presses tumor formation remain unclear. DNA damage regulates both the protein levels of p53 and its affinity for specific DNA sequences. Stabilization of p53 in response to DNA damage is caused by its dissociation from Mdm2, a downstream target gene of p53 and a protein that targets p53 for degradation in the proteosome. Recent studies have suggested that phosphorylation of human p53 at Ser20 is important for stabilizing p53 in response to DNA damage through disruption of the interaction between Mdm2 and p53. We generated mice with an allele encoding changes at Ser20, known to be essential for p53 accumulation following DNA damage, to enable analyses of p53 stabilization in vivo. Our data showed that the mutant p53 was clearly defective for full stabilization of p53 in response to DNA damage. We concluded that Ser20 phosphorylation is critical for modulating the negative regulation of p53 by Mdm2, probably through phosphorylation-dependent inhibition of p53-Mdm2 interaction in the physiological context.

High-performance hybrid plastic films: a robust electrode platform for thin-film optoelectronics

Jin, Jungho,Lee, Jaemin,Jeong, Seonju,Yang, SeungCheol,Ko, Ji-Hoon,Im, Hyeon-Gyun,Baek, Se-Woong,Lee, Jung-Yong,Bae, Byeong-Soo The Royal Society of Chemistry 2013 Energy & environmental science Vol.6 No.6

<P>We report a novel flexible hybrid plastic film that can be used as a robust electrode platform for typical thin-film optoelectronic devices. Silver nanowires (AgNWs) were embedded on the surface of a glass-fabric reinforced transparent composite (GFRHybrimer) film to form a flexible transparent conducting substrate with excellent opto-electrical properties, superior thermal stability, and impressive mechanical flexibility. A highly efficient and flexible inverted organic solar cell with a power conversion efficiency (PCE) of 5.9% under 100 mW cm<SUP>−2</SUP> AM 1.5G illumination was fabricated on the AgNW–GFRHybrimer film. The AgNW–GFRHybrimer film exhibits potential as an excellent transparent electrode for low cost flexible optoelectronic devices.</P> <P>Graphic Abstract</P><P>A flexible hybrid film is proposed as a robust electrode for thin-film optoelectronic devices: a silver nanowire embedded glass-fabric reinforced hybrimer. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c3ee24306k'> </P>

Spark Streaming 기반 시스템에서 실시간 고장 복구를 지원하기 위한 고장 복구 시간 추정과 체크포인팅 기법

김정호(Jungho Kim),양범준(Beomjoon Yang),이은성(Eunseong Lee),홍성수(Seongsoo Hong) 한국정보과학회 2016 한국정보과학회 학술발표논문집 Vol.2016 No.6

Insights into constitutional isomeric effects on donor-acceptor intermolecular arrangements in non-fullerene organic solar cells

Lee, Jungho,Go, Eun Min,Dharmapurikar, Satej,Xu, Jianqiu,Lee, Sang Myeon,Jeong, Mingyu,Lee, Kyu Cheol,Oh, Jiyeon,Cho, Yongjoon,Zhang, Chunfeng,Xiao, Min,Kwak, Sang Kyu,Yang, Changduk The Royal Society of Chemistry 2019 Journal of Materials Chemistry A Vol.7 No.31

<P>Donor-acceptor intermolecular interactions and/or arrangements are key factors determining the performance of organic solar cells (OSCs). Herein, two ITIC-based isomeric acceptors (<I>o</I>-F-ITIC and <I>m</I>-F-ITIC) with fluorine atoms at <I>ortho</I> and <I>meta</I> positions within the side chains were developed. The developed acceptors showed different interactions and/or arrangements with the donor counterpart (PBDB-T), which caused a significant variation in the power conversion efficiency (PCE) of OSCs. The PCE of the PBDB-T:<I>o</I>-F-ITIC device was 11.11% <I>versus</I> 8.90% of the PBDB-T:<I>m</I>-F-ITIC device. A detailed theoretical analysis of the intermolecular complexes formed between F-ITICs and PBDB-T allows a determination of how the two isomeric acceptors interact differently with PBDB-T. Relative to PBDB-T:<I>m</I>-F-ITIC with a preferential DCI-BDD complex, PBDB-T:<I>o</I>-F-ITIC showed a closer donor-acceptor interaction, with a tightly packed parallel-like DCI-BDT complex, resulting in larger interfacial areas. These behavioral characteristics explain in detail the experimental results obtained from the comparison of the two blend systems relating to electrical and morphological properties. Moreover, transient absorption spectroscopy of PBDB-T:<I>o</I>-F-ITIC revealed superior hole/electron transfer and separation processes, providing further evidence of the presence of beneficial intermolecular complexes. This study facilitates the understanding of the role of constitutional isomerism both in intermolecular interactions and in promoting the development of high-performance OSCs.</P>